1. Field of the Invention
The present invention relates to a camera employing a film with a magnetic recording section, and more particularly to a camera using a film with a magnetic recording section, with the camera being equipped with a magnetic head having a magnetic gap portion for recording or reading (reproducing) information and further equipped with a pressure pad (pressing member) for pressing the magnetic recording section (film surface) of the film against the magnetic head.
2. Related Background Art
Recently, the so-called films with a magnetic recording section have variously been proposed as roll films taken for photography and actually put to practical use, wherein a magnetic recording section is placed on a film surface for allowing the magnetic recording of information. In addition, cameras employing the film with the magnetic recording section have also been proposed in various ways.
Such cameras employing a film with a magnetic recording section are equipped with a magnetic head with a magnetic gap whereby information is recorded on the magnetic recording section of the film or information recorded is read out (reproduced) therefrom, that is, this magnetic head accomplishes the magnetic recording and reading of information. Further, in general a pressure pad (pressing member) is provided to press the magnetic recording section against the magnetic head, thereby ensuring the information is recorded and read by the magnetic head.
More specifically, for making sure the magnetic recording and reading of information by the magnetic head, it is necessary for the magnetic gap portion of the magnetic head to be correctly brought into contact with the magnetic recording section of the film. For this reason, in the prior art, a pressure pad (pressing member) is pressed against the magnetic head through the use of a biasing member or the like, or as will be described later, both the magnetic head and pressure pad respectively have biasing members so as to be pressed against each other, so that the film is caught in between the magnetic head and the pressure pad to allow the film magnetic recording section to be correctly placed into contact with the magnetic gap portion of the magnetic head.
Furthermore, for ensuring the appropriate contact of the magnetic gap portion of the magnetic head with the magnetic recording section of the film, commonly the surface of the magnetic head having the magnetic gap portion, i.e., the contact surface with the film, is shaped into an arc configuration.
That is, in a magnetic recording apparatus applicable to the prior cameras, as shown in FIG. 17, a magnetic head 101 with a magnetic gap portion 101a is located on the rear side of the camera, i.e., on the side of a pressure plate 106 placed for keeping the flatness of the film surfaces in a state where a biasing member 104b is interposed between the magnetic head 101 and the pressure plate 106, while a pressure pad 103 is situated on the side of a camera body 105 in a state where a biasing member 104a is sandwiched between the pressure pad 103 and the camera body 105, with the pressure pad 103 being positioned in opposed relation to the magnetic head 101 so that a film feeding passage in which a film 102 set in the camera travels is defined between the magnetic head 101 and the pressure pad 103. Further, the magnetic head 101 and the pressure pad 103 are biased to press against each other by the biasing forces of the biasing members 104a, 104b to hold the film 102 therebetween.
Still further, for ensuring the magnetic recording and reading by the magnetic head 101, the surface of the magnetic head 101 which has the magnetic gap portion 101a is made to have an arc configuration with respect to a plane in the film traveling direction (the arrow X direction in FIG. 17) so that the magnetic gap portion 101a can appropriately be brought into contact with the magnetic recording section of the film 102 and the contact between the magnetic gap portion 101a and the film 102 becomes facilitated.
A description will be made hereinbelow of the disposition of a magnetic head and a pressing member organizing a magnetic recording apparatus in a prior camera employing a film with a magnetic recording section, which has been proposed and put to practical use.
That is, as shown in FIG. 18, in the afore said prior camera, a magnetic head 101 with a magnetic gap portion 101a is fixedly secured to a stationary member on the rear side of the camera, whereas a pressing member 103 is placed on the side of a camera body 105 to be in opposed relation to the magnetic head 101 so that a film 102 is interposed therebetween, with a biasing member 104a being put in between the pressing member 103 and the camera body 105. Thus, the film 102 is sandwiched between the magnetic head 101 and the pressing member 103 and the pressing member 103 is biased by the biasing force of the biasing member 104a in the direction of being pressed against the magnetic head 101 side.
In addition, for making sure the magnetic recording and reading by the magnetic head 101, the surface of the magnetic head 101 having the magnetic gap portion 101a, i.e., the film contact surface, is made to have an arc configuration with respect to a plane in the film traveling direction (the arrow X direction in FIG. 18) so that the magnetic gap portion 101a can correctly be brought into contact with the magnetic recording section of the film 102 and the contact between the magnetic gap portion 101a and the film 102 becomes easy.
Furthermore, for the correct contact of the magnetic head in the camera with the magnetic recording section of the film to ensure the magnetic recording and reading, through the use of the biasing force of the biasing member the pressing member is made to be biased toward the magnetic gap portion of the magnetic head in a state where the film is put in therebetween. For example, there are an apparatus employing the so-called swinging type pressing member as shown in FIG. 19 and an apparatus in which a plate spring is used as the biasing member for pushing the pressing member against the magnetic head side as shown in FIG. 20.
In the apparatus employing the swinging type pressing member, as shown in FIG. 19 a step portion 103A is formed at a proximal section of a pressing member 103a and a shaft portion 103 is planted and one end portion of a biasing member 104 comprising an extensible coil spring is fixedly secured to the step portion 103A. Further, the other end portion of the same biasing member 104 is brought into contact with a stationary member on the camera body 105 side so that the pressing member 103 is vertically biased toward the magnetic head 101 side by means of the biasing force of the biasing member 104 in a state where a film 102 is interposed therebetween. The tip portion 103c of the shaft portion 103 is engaged with a recess portion 103B on the camera body 105 side, with the result that the pressing member 103a is always situated at the position facing the magnetic gap portion 101a of the magnetic head 101.
In this case, the engagement between the step portion 103A of the pressing member 103a and the camera body 105 and the engagement between the shaft portion 103c and the recess portion 103B on the camera body 105 side are not made in a state where they come closely into contact with each other. Accordingly, when the magnetic head 101 and the pressing member 103a are pressed against each other in a state where the film 102 is put therebetween, on the feed of the film the pressing member 103a follows the film 102 to swing in the film feeding direction.
More specifically, engagement looseness slightly occurs in the engaging portion between the step portion 103A and the camera body 105 and between the shaft portion 103c and the recess portion 103B on the camera body 105 side. Owing to the presence of this engagement looseness, when the film 102 is fed in the direction indicated by an arrow X in FIG. 19, a friction F occurs between the film contact surface of the pressing member 103a and the film 102, thereby swinging the pressing member 103.
On the other hand, in the case of the apparatus employing a plate spring as the biasing member, as shown in FIG. 20 a pressing member 103b is fitted to the free end portion of a plate spring 104A serving as the biasing member whose proximal portion is cantilevered by a supporting pin 106 on a camera body 105, and this pressing member 103b is biased toward a magnetic gap portion 101a of a magnetic head 101 by means of the biasing force of the plate spring 104A.
In addition, means for correctly bringing a magnetic head in a camera into contact with a magnetic recording section on a film surface to secure the magnetic recording and reading has been proposed, for example, through Japanese Unexamined Patent Publication No. 3-168624. In the camera disclosed in Japanese Unexamined Patent Publication No. 3-168624, a magnetic head and a pressing member (pressure pad) are located to be in opposed relation to each other in a state in which a film is put therebetween, and the magnetic head is biased by a biasing member comprising an extensible spring while the pressing member is biased by a biasing member comprising a plate spring so that they are pressed against each other to hold the magnetic recording section of the film, thereby improving the contact condition between the magnetic head and the film and minimizing the adverse influence on the photographed scene due to the distortion or deformation of the film.
In the case of the apparatus equipped with the film contact surface of the magnetic head having an arc configuration as shown in FIG. 18 or disclosed in Japanese Unexamined Patent Publication No. 3-168624, as shown in FIG. 21 there is a possibility that a magnetic gap portion 101a of a magnetic head 101 is assembled in a state of being inclined by an angle .alpha. with respect to a surface of a film 102 due to the dimensional errors and fitting errors of the components or the like. In FIG. 21, an arrow X represents the film feeding direction.
In this case, it is difficult that the magnetic gap portion 101a correctly comes into contact with the magnetic recording section of the film 102, with the result that difficulty is encountered to surely perform the magnetic recording and reading.
Thus, a technical means to solve such a problem is exemplified by Japanese Unexamined Patent Publication No. 4-11237.
In a camera disclosed in Japanese Unexamined Patent Publication No. 4-11237, there are provided a magnetic head and a pressing member for pressing a film surface against the magnetic head side through the biasing force of a biasing member. Further, a pressure pad is placed to be swingable in the film traveling direction and the film contact surface of the pressure pad is made to have a U-like cross-sectional configuration, so that, even if a trouble about the fitting positions of the magnetic head and the pressure pad occurs due to the dimensional errors and fitting errors of the respective components, the magnetic head and the magnetic recording section of the film can stably come into contact with each other.
Furthermore, in a camera disclosed in Japanese Unexamined Patent Publication No. 6-282006, a magnetic head is disposed to be inclined by a given angle with respect to the film traveling direction so that its magnetic gap portion substantially vertically comes into contact with a magnetic recording section of a film.
With this structure, the contact condition of the magnetic gap portion with respect to the film magnetic recording section is improvable and the flatness of the film is also improvable.
On the other hand, in the case of the swinging type pressing member 103 mentioned referring to FIG. 19, when the film 102 is not loaded yet in the camera, it is biased in the direction perpendicular to the magnetic head 101. However, if the film 102 is loaded therein and fed, the pressing member 103 follows the film 102 to swing in the film feeding direction, with the result that the pressing member 103 is inclined by an angle .theta. as shown in FIG. 19.
Accordingly, difficulty is experienced to ensure the correct contact between the magnetic gap portion 101a of the magnetic head 101 and the magnetic recording section of the film 102, thus resulting in unsatisfactory magnetic recording and reading.
Still further, in the case of employing the pressing member using a plate spring mentioned with reference to FIG. 20, in a state where the film 102 is not loaded in the camera, the magnetic head 101 and the pressing member 103b are disposed to face each other in parallel. On the contrary, if the film 102 is loaded in the camera and fed, as shown in FIG. 22 the film 102 is put between the magnetic head 101 and the pressing member 103, and in this case, the pressing member 103b is pushed down against the biasing force of the plate spring 104A.
More specifically, the pressing member 103b, together with the plate spring 104A, is rotated clockwise in FIG. 22 in a manner that the supporting pin 106 serves as a supporting shaft. Whereupon, the pressing member 103b takes a condition inclined by an angle .beta. with respect to the magnetic gap portion 101a.
For this reason, the correct control becomes impossible between the magnetic gap portion 101a of the magnetic head 101 and the magnetic recording section of the film 102, and as in the case of the aforesaid swinging type pressing member, difficulty is encountered to certainly accomplish the magnetic recording and reading.
Moreover, in the case of the means shown in FIG. 18 or disclosed in Japanese Unexamined Patent Publication No. 3-168624, if as described with reference to FIG. 21 the magnetic gap portion 101a of the magnetic head 101 is assembled in a state of being inclined with respect to the film 102 surface due to the dimensional errors and fitting errors of the components or the like, the magnetic gap portion 101a can not correctly be placed into contact with the magnetic recording section of the film 102, which makes difficult to ensure magnetic recording and reading.
Accordingly, for preventing the magnetic recording section of the film 102 from rising from the magnetic gap portion 101a, it is considered that, for example, the biasing members 104a working for the magnetic head 101 and the pressing member 103 is set to have a stronger biasing force.
However, since the film 102 is fed in a state of being placed between the magnetic head 101 and the pressing member 103, if the biasing force of the biasing member 104a increases, the load on the film 102 during the feeding becomes larger so that not only the consumption of the power battery increases but also it is impossible to perform the film feeding at a constant speed, with the result that the magnetic recording and reading to be done during the film feeding becomes difficult.
In addition, in the case of strengthening the biasing force of the biasing member 104a, the film contact surface of the magnetic head 101 can damage or destroy the film 102.
Moreover, in the camera disclosed in Japanese Unexamined Patent Publication No. 4-11237, if as shown in FIG. 23 a magnetic gap portion 101a and the swinging center 107 of a pressing member 103d are assembled in a state of being shifted by a distance indicated by character A from a given position, the pressing member 103d is inclined by an angle .gamma.. Accordingly, in this case, in a state where a film 102 is not mounted in the camera, it is impossible to ensure a satisfactory separation between the magnetic head 101 and the pressing member 103d.
For this reason, in this state, when the film 102 is loaded in the camera and fed (the feeding direction is the direction indicated by an arrow X in FIG. 23), the tip portion of the film 102 can not pass through the separation between the magnetic head 101 and the pressing member 103d, so that the film 102 stops.
Accordingly, in order to avoid the stopping of the film 102 in this state, there is a need for a mechanism which moves at least one of the pressing member 103 and the magnetic head 101 to enlarge the separation between the magnetic head 101 and the pressing member 103d. However, if employing such a mechanism, the camera itself increases in size and the manufacturing cost increases.
On the other hand, like the means shown in FIG. 17 or disclosed in Japanese Unexamined Patent Publication No. 3-168624 or 4-11237, in the case that the magnetic head and the pressure pad are constructed to be pressed against each other by the biasing forces of the biasing members, the pressure pad is always pressed against the film surface by the biasing member even while the film travels for feeding. Accordingly, as the camera is more frequently used for photography, more abrasion occurs because the film surface travels while being brought into contact with the pressure pad. Whereupon, the contact condition between the magnetic gap portion of the magnetic head and the magnetic recording section on the film surface varies from the initial state, and the continuous use makes it difficult to secure the magnetic recording and reading of information.
Furthermore, as described above, when the contact surface of the pressure pad wears out by the film surface, powder is produced due to the abrasion of the pressure pad, and if this abrasion powder attaches to the magnetic gap portion of the magnetic head, the abrasion powder hinders the contact between the magnetic recording section on the film surface and the magnetic gap portion, which makes it difficult to surely accomplish the magnetic recording and reading of information.
Still further, when the film feeding operation is conducted in a state where the film surface and the pressure pad are placed into contact with each other, in the case of a common pressure pad, static electricity occurs because of the sliding contact between the film surface and the pressure pad, so that the abrasion powder tends to be absorbed by the film surface. In addition, in a state where the film is not loaded in the camera, the magnetic head and the pressure pad are placed into direct contact with each other, with the result that the abrasion powder absorbed by the pressure pad can be transferred from the pressure pad side to the magnetic head side due to static elasticity. If in this state the film is loaded in the camera, as described above, the abrasion powder hinders the contact between the magnetic recording section of the film and the magnetic gap portion, thereby making it difficult to certainly perform magnetic recording and reading.
Moreover, if static electricity occurs between the film surface and the pressure pad due to the film feeding, the discharge of this static electricity can make the emulsion surface of a non-exposed section of the film partially exposed, that is, the camera can suffer from troubles such as the so-called color fog.